Kakouen is an assassin from Kyosho, who's only aim in life is to protect and serve Sousou. Her loyalty to Sousou lies when she was just a child, being forced to participate in a war, where she met and was saved by Sousou, who gives her a new life.

Kakouen is first seen trying to take the Dragon Jade from Ryomou, as she was ordered to by her leader at Kyosho academy. Kakouen then fights Ryomou, do to Ryomou unwillingness to give the Dragon Jade, and the shrine which contained the Dragon Jade collapses, allowing Ryomou to escape from Kakouen.

Kakouen, although dirtied, did not give up on her pursuit of the Dragon Jade, and finds where Ryomou was staying at, a hotel. She beats up the manager and goes to the room Ryomou was at only to find that Ryomou had already known of her presence. Ryomou is able to kick a couch to Kakouen, allowing her to escape once again.

Kakouen is next seen, being ordered, by a newly fired, Kaku, who tells her to get the Dragon Jade, as it was the only way to save Sousou's life.

Kakouen then breaks into Nanyo, fightining and beating many fighters, until she gets to Gakushuu, who was able to hold her for a while, but Kakouen eventually got serious easily gaining the upper hand on Gakushuu. Although she found it a waste of her time as Ryomou, who has the Dragon Jade, was not here.

Kakouen is next seen with the Kyosho team, ready to fight at the battle of Red cliffs. She was ordered to get the Dragon Jade, by Shibai, which she tries to do, but is met with Ryomou. They then fight, and although Kakouen was able to outmatch Ryomou, the combination of both Ryomou, and Saji's Chi blast was too much for her, and she was defeated on impact.

Kakouen is revealed to be alive and in charge of Kyosho Academy due to the absence of Sousou and Kakouton. In the aftermath of the Battle of Red Cliffs, she seemed determined to restore Kyosho's former glory and power and was desperately searching for any sign of her beloved leader Sousou. When approached by a mysterious girl (the real Genpou Saji) with a deal to recover the missing Kakouton, Kakouen warily accepted. Afterwards, Kakouen worked with Ouin and distracted Kakouton while Ouin made off with Ryofu. As she was about to finish Kakouton, she was interrupted by Hakufu. In the end, Kakouen was defeated by Kakouton, who tells her that he will find his own way to Sousou and return to Kyosho when he is ready. Later, under the influence of the real Saji's genjutsu, she viciously fights Kakouton and Koukin, only to be interrupted by Sousou's return which breaks her hypnotized state. She then returned to Kyosho with Kakouton and Sousou.